The present invention relates to an optical disc, its recording method, its recording device, its reproducing method, and its reproducing device. More specifically, it relates to an optical disc having a recognition mark area behind a recorded area, its recording method, its recording device, its reproducing method, and its reproducing device.
An optical disc is a high-density information recording medium in which information is recorded by using a semiconductor laser and is reproduced by using the difference in the reflectance of light beams between a recorded part and an unrecorded part.
The optical disc is provided with one or a plurality of xe2x80x9crecorded area(s)xe2x80x9d in which a predetermined information signal is written. xe2x80x9cAn unrecorded areaxe2x80x9d in which a new information signal can be written is provided outside the recorded area. In particular, in order to reproduce an optical disc on which recording has been performed several times, it is necessary to know the number of the recorded areas of the disc. In other words, it is necessary to detect xe2x80x9cthe last recorded areaxe2x80x9d of the disc to be reproduced. In this way, in order to detect the last recorded area of the disc to be reproduced, it is necessary to access the recorded areas sequentially from the first recorded area by moving the optical head repeatedly. However, it is impossible to know whether a succeeding recorded area exists or not before the optical head is moved to the position, and when the optical head is moved to an unrecorded area, servo control cannot be performed, thus bringing about an abnormal state.
Therefore, in a reproducing method for an optical disc described in Published Unexamined (Kokai) Japanese Patent Application No. Hei 6-349252, an address of a lead-out area is readded at a lead-in area provided in the first position of the recorded area, and then this lead-out area is accessed. Next, an optical head is moved to the succeeding recorded area by repeating one or more jump of one track or a plurality of tracks in the direction to the outer circumference. When it is decided that the optical head reaches the unrecorded area, the optical head is returned toward the inner circumference side without turning on the tracking servo. According to this method, an abnormal state due to the disability of the servo control is prevented.
However, in the reproducing method for the optical disc described in the above-mentioned publication, the optical head cannot be prevented from reaching the unrecorded area in detecting xe2x80x9cthe last recorded area.xe2x80x9d Therefore, it becomes necessary to perform an operation of returning the optical head toward the inner circumference side without turning on the tracking servo. Thus, xe2x80x9cthe last recorded areaxe2x80x9d cannot be detected efficiently.
Recently, a technique is suggested, in which a recognition mark area for recognizing whether the succeeding area is an unrecorded area or not is provided just behind the last data in the recorded area, and the state of the recognition mark area is detected by the behavior when the recognition mark area is accessed, thereby determining whether the area behind the recognition mark area is an unrecorded area or a recorded area (whether the recorded area is the last recorded area or not). In this technique, when the recognition mark area cannot normally be accessed, the succeeding area is determinined to be the unrecorded area. In this case, when the recognition mark area is accessed, first, the lead-in data at the head of the recorded area is accessed so as to obtain the address of the lead-out area, and then the address of the recognition mark area existing in the vicinity of the head of the lead-out area is accessed. When a new information signal is written in the unrecorded area, a reproducible recording mark that does not cause a data error is recorded in the recognition mark area, and at the same time a new recognition mark area is provided behind the area in which the new information signal is written (the new recorded area).
However, in the above-mentioned marking method, when the recognition mark area is provided just behind the last data in the recorded area, if an access error exists when the last data in the recorded area is accessed, the optical head wrongly jumps to the recognition mark area, which may lead to an unstable access operation. Furthermore, when the recognition mark area is provided just before the unrecorded area, the optical head jumps to the unrecorded area at the time of accessing the recognition mark area, thus bringing about an abnormal state due to the disability of the servo control. In addition, if a succeeding recorded area exists, when the first data in the succeeding recorded area is accessed, the optical head jumps to the recognition mark area, thus bringing about an unstable access operation.
The present invention is intended to overcome the above-mentioned problem according to the prior art. It is therefore an object of the present invention to provide an optical disc in which a last data in the recorded area is stably accessed, a recognition mark area can be accessed without bringing about an abnormal state, and the first data in a succeeding recorded area, if it exists, is stably accessed, its recording method, its recording device, its reproducing method and its reproducing device.
In order to achieve the above-mentioned object, a first configuration of the optical disc according to the present invention has a concentric or spiral information track, and, behind a recorded area in which information is recorded on the information track, a first buffer area having a width wider than an access error when the last data in the recorded area is accessed, and a recognition mark area are recorded. According to the first configuration of the optical disc, since the optical head can be prevented from jumping to the recognition mark area when the reproducing device accesses the last data in the recorded area, a stable access operation can be realized in any one of states selected from a state in which no recording mark exists in the recognition mark area and a state in which a non-reproducible recording mark is formed.
Furthermore, it is preferable in the above-mentioned first configuration of the optical disc according to the present invention that the width of the first buffer area is 20 tracks or more and 100 tracks or less. It is preferable that the first buffer area be as small as possible since it greatly consumes the recorded area of the optical disc, however, in the access of the reproducing device for the optical disc, an error corresponding to several tens of tracks generally occurs.
Furthermore, it is preferable in the above-mentioned first configuration of the optical disc according to the present invention that the width of the recognition mark area is 2 tracks or less. In order to prevent the tracking from easily being off and to perform the detection and relead-in promptly if the tracking-off occurs, the width of the recognition mark area is desired to be as short as possible. However, in order to record a reproducible recording mark on the recognition mark area that does not bring about a data error, it is necessary to record the reproducible recording mark using the block length for correcting error as a unit. Therefore, the width of the recognition mark area is required to be the length corresponding to the block length for correcting error. Moreover, it is desirable that the width of the recognition mark area is twice or more the block length for correcting error in order to avoid an incorrect recognition even if a data error occurs at the time of reproducing information. For example, in the case of a DVD disc, twice the block length for correcting error is 0.5 tracks to 1.1 tracks. Thus, it is possible to record the reproducible recording mark when the width of the recognition mark area is 2 tracks or less. Therefore, it is preferable that the width of the recognition mark area is 2 tracks or less.
Furthermore, it is preferable in the above-mentioned first configuration of the optical disc according to the present invention that the recognition mark area is in any of states selected from the group consisting of a state in which no recording mark exists, a state in which a reproducible recording mark is formed and a state in which a non-reproducible recording mark is formed.
Furthermore, it is preferable in the above-mentioned first configuration of the optical disc according to the present invention that, behind the recognition mark area, a second buffer area having a width wider than an access error when the recognition mark area is accessed is further recorded. According to such a preferable example, when the recognition mark area is accessed, the optical head can be prevented from jumping to the unrecorded area due to an access error. Furthermore, even if the servo is skipped in the recognition mark area, the optical head is relead-in by the time when it reaches the unrecorded area. Therefore, the optical head can be prevented from jumping to the unrecorded area. Moreover, when the first data in a succeeding area, if it exists, is accessed, the optical head can be prevented from jumping to the recognition mark area. As a result, an unstable access operation or an abnormal state due to the disability of the servo control can be avoided. In this case, it is further preferable that the width of the second buffer area is 20 tracks or more and 100 tracks or less. It is preferable that the second buffer area be as small as possible since it greatly consumes the recorded area of the disc, however, in the access of the reproducing device for the optical disc, an error corresponding to several tens of tracks generally occurs. Furthermore, when the tracking is off in the recognition mark area, the total number of the track traversal number that is required to detect the tracking off and the track traversal number generated following the releading-in process after the tracking is off generally becomes several tracks.
Furthermore, a second configuration of the optical disc according to the present invention has a concentric or spiral information track, and a first buffer area having the width of 20 tracks or more and 100 tracks or less, a recognition mark area having the width of 2 tracks or less, and a second buffer area having the width of 20 tracks or more and 100 tracks or less are recorded behind each of N (wherein N is a natural number) recorded areas in which information is recorded on the information track.
Furthermore, a third configuration of the optical disc according to the present invention has a concentric or spiral information track, and a plurality of units including a recorded area in which information is recorded on the information track, a first buffer area being provided behind the recorded area and having the width of 20 tracks or more and 100 tracks or less, a recognition mark area having the width of 2 tracks or less and a second buffer area having the width of 20 tracks or more and 100 tracks or less are continuously recorded. The recorded state of the last recognition mark area among the plurality of recognition mark areas is different from the recorded states of the other recognition mark areas. According to the third configuration of the optical disc, the last recorded area can be identified by determining the recorded state of the recognition mark area.
Furthermore, it is preferable in the above-mentioned third configuration of the optical disc according to the present invention that the recognition mark area is in any of states selected from the group consisting of a state in which no recording mark exists, a state in which a reproducible recording mark is formed and a state in which a non-reproducible recording mark is formed.
Furthermore, in a first recording method for an optical disc according to the present invention, information is recorded by irradiating an information track of an optical disc with a light beam generated from a light source and by modulating the strength of said light beam in accordance with recording signals. Following the recording of a predetermined information, a first buffer area having a width wider than an access error when the last data in said predetermined information and a recognition mark area are recorded.
Furthermore, it is preferable in the first recording method for an optical disc according to the present invention that the width of the first buffer area is set to be 20 tracks or more and 100 tracks or less.
Furthermore, it is preferable in the first recording method for an optical disc according to the present invention that the width of the recognition mark area is set to be 2 tracks or less.
Furthermore, it is preferable in the first recording method for an optical disc according to the present invention that the recognition mark area is in any of states selected from the group consisting of a state in which no recording mark exists, a state in which a reproducible recording mark is formed and a state in which a non-reproducible recording mark is formed.
Furthermore, it is preferable that the first recording method for an optical disc according to the present invention that, behind the recognition mark area, a second buffer area having a width wider than an access error when the recognition mark area is accessed is further recorded. Furthermore, in this case, it is preferable that the width of the second buffer area is set to be 20 tracks or more and 100 tracks or less.
Furthermore, in a second recording method for an optical disc according to the present invention, information additionally is recorded on the optical disc in which, behind a recorded area in which information is recorded on a concentric or spiral information track, a first buffer area having a width wider than an access error when the last data in the recorded area is accessed, a recognition mark area and a second buffer area having a width wider than an access error when the recognition mark area is accessed are recorded. The method comprises the steps of irradiating the information track of the optical disc, which is made to rotate, with a light beam generated from a light source; controlling the light beam to be positioned on the information track in the recognition mark area; changing the state of the recognition mark area by modulating the strength of the light beam; retrieving a recordable area in which information can be additionally recorded and controlling the light beam to be positioned on the information track in the recordable area; and modulating the strength of the light beam in accordance with signals to be additionally recorded and recording the additional information. According to the second recording method for an optical disc, when the additional information is recorded, the state of the recognition mark area is changed. Consequently, it can be decided whether the succeeding area is a recorded area or an unrecorded area by determining the state of the recognition mark area.
Furthermore, it is preferable in the above-mentioned second recording method for an optical disc according to the present invention that the state of the recognition mark area is changed and then the additional information is recorded on the information track in the recordable area.
Furthermore, it is preferable in the above-mentioned second recording method for an optical disc according to the present invention that the additional information is recorded on the information track in the recordable area and then the state of the recognition mark area is changed.
Furthermore, it is preferable in the above-mentioned second recording method for an optical disc according to the present invention that, behind the recorded area in which the additional information is recorded, the first buffer area having a width wider than an access error when the last data of the additional information in the recorded area is accessed and the recognition mark area are recorded. In this case, it is further preferable that the width of the first buffer area is set to be 20 tracks or more and 100 tracks or less. In this case, it is further preferable that the width of the recognition mark area is set to be 2 tracks or less. In this case, it is further preferable that, behind the recognition mark area, the second buffer area having the width wider than an access error when the recognition mark area is accessed. In this case, it is still further preferable that the width of the second buffer area is set to be 20 tracks or more and 100 tracks or less.
Furthermore, a first configuration of a recording device for an optical disc according to the present invention comprises a rotating means for rotating an optical disc having a concentric or spiral information track, an optical head irradiating the information track with light beam generated from a light source, a control means for controlling the light beam to be positioned on the information track, a modulating means for modulating the strength of the light beam in accordance with information signals to be recorded, wherein the light beam is modulated by the modulating means and, behind a recorded area in which a predetermined information is recorded on the information track, a first buffer area having a width wider than an access error when the last data of the predetermined information is accessed and a recognition mark area are recorded.
Furthermore, it is preferable in the above-mentioned first configuration of a recording device for an optical disc according to the present invention that the width of the first buffer area is set to be 20 tracks or more and 100 tracks or less.
Furthermore, it is preferable in the above-mentioned first configuration of a recording device for an optical disc according to the present invention that the width of the recognition mark area is set to be 2 tracks or less.
Furthermore, it is preferable in the above-mentioned first configuration of a recording device for an optical disc according to the present invention that the recognition mark area is in any of states selected from the group consisting of a state in which no recording mark exists, a state in which a reproducible recording mark is formed and a state in which a non-reproducible recording mark is formed.
Furthermore, it is preferable in the above-mentioned first configuration of a recording device for an optical disc according to the present invention that, behind the recognition mark area, a second buffer area having a width wider than an access error when the recognition mark area is accessed is further recorded. In this case, it is further preferable that the width of the second buffer area is set to be 20 tracks or more and 100 tracks or less.
Furthermore, a second configuration of a recording device for an optical disc according to the present invention, information being additionally recorded on the optical disc in which, behind a recorded area in which information is recorded on a concentric or spiral information track, a first buffer area having a width wider than an access error when the last data in the recorded area is accessed, a recognition mark area and a second buffer area having a width wider than an access error when the recognition mark area is accessed are recorded, comprises
a rotating means for rotating the optical disc, an optical head for irradiating the information track with light beam generated from a light source, a retrieving means for retrieving the target information track and controlling the light beam to be positioned on the target information track, and a modulating means for modulating the strength of the light beam:
wherein, when new information is additionally recorded on the optical disc, the information track of the recordable area in which information can be recorded is retrieved by the retrieving means, and then information is additionally recorded on the information track of the recordable area by modulating the strength of light beam in accordance with signals to be additionally recorded by the modulating means, while the recognition mark area is retrieved by the retrieving means, and then the state of the recognition mark area is changed by modulating the strength of the light beam by the modulating means.
Furthermore, it is preferable in the above-mentioned second configuration of a recording device for an optical disc according to the present invention that the state of the recognition mark area is changed and then the additional information is recorded on the information track in the recordable area.
Furthermore, it is preferable in the above-mentioned second configuration of a recording device for an optical disc according to the present invention that the additional information is recorded on the information track in the recordable area and then the state of the recognition mark area is changed.
Furthermore, it is preferable in the above-mentioned second configuration of a recording device for an optical disc according to the present invention that, behind the recorded area in which the additional information is recorded, the first buffer area having a width wider than an access error when the last data of the additional information in the recorded area is accessed and the recognition mark area are recorded. In this case, it is further preferable that the width of the first buffer area is set to be 20 tracks or more and 100 tracks or less. In this case, it is further preferable that the width of the recognition mark area is set to be 2 tracks or less. In this case, it is further preferable that, behind the recognition mark area, a second buffer area having a width wider than an access error when the recognition mark area is accessed is further recorded. In this case, it is further preferable that the width of the second buffer area is set to be 20 tracks or more and 100 tracks or less.
Furthermore, a reproducing method for an optical disc according to the present invention, information being reproduced from the optical disc in which, behind a recorded area in which information is recorded on a concentric or spiral information track, a first buffer area having a width wider than an access error when the last data in the recorded area is accessed, a recognition mark area are recorded, the method comprising the steps of:
irradiating the information track of the optical disc, which is made to rotate, with light beam generated from a light source; retrieving the recognition mark area; determining the state of the recognition mark area; and specifying the recorded area in which recording is completed based on the determined state of said recognition mark area and reproducing information of the specified recorded area.
Furthermore, it is preferable in the above-mentioned reproducing method for an optical disc according to the present invention that the width of the first buffer area is set to be 20 tracks or more and 100 tracks or less.
Furthermore, it is preferable in the above-mentioned reproducing method for an optical disc according to the present invention that the width of the recognition mark area is 2 tracks or less.
Furthermore, it is preferable in the above-mentioned reproducing method for an optical disc according to the present invention that the recognition mark area is in any of states selected from the group consisting of a state in which no recording mark exists, a state in which a reproducible recording mark is formed and a state in which a non-reproducible recording mark is formed.
Furthermore, it is preferable in the above-mentioned reproducing method for an optical disc according to the present invention that, behind the recognition mark area, a second buffer area having a width wider than an access error when the recognition mark area is accessed is further recorded on the optical disc. In this case, it is further preferable that the width of the second buffer area is set to be 20 tracks or more and 100 tracks or less.
Furthermore, a first configuration of a reproducing device for an optical disc according to the present invention, information being reproduced from the optical disc in which, behind a recorded area in which information is recorded on a concentric or spiral information track, a first buffer area having a width wider than an access error when the last data in the recorded area is accessed, a recognition mark area are recorded, comprising:
a rotating means for rotating the optical disc, an optical head for irradiating the information track with light beam generated from a light source; and a retrieving means for retrieving the target information track; wherein the state of the recognition mark area is determined by retrieving the recognition mark area by the retrieving means, the recorded area in which recording is completed being identified based on the determined state of the recognition mark area.
Furthermore, it is preferable in the above-mentioned first configuration of a reproducing device for an optical disc according to the present invention that the width of the first buffer area is set to be 20 tracks or more and 100 tracks or less.
Furthermore, it is preferable in the above-mentioned first configuration of a reproducing device for an optical disc according to the present invention that the width of the recognition mark area is set to be 2 tracks or less.
Furthermore, it is preferable in the above-mentioned first configuration of a reproducing device for an optical disc according to the present invention that the recognition mark is in any of states selected from the group consisting of a state in which no recording mark exists, a state in which a reproducible recording mark is formed and a state in which a non-reproducible recording mark is formed.
Furthermore, it is preferable in the above-mentioned first configuration of a reproducing device for an optical disc according to the present invention that, behind the recognition mark area, a second buffer area having a width wider than an access error when the recognition mark area is accessed is further recorded on the optical disc. In this case, it is further preferable that the width of the second buffer area is set to be 20 tracks or more and 100 tracks or less.
Furthermore, a second configuration of a reproducing device for an optical disc according to the present invention, information being reproduced from the optical disc in which, behind a recorded area in which information is recorded on a concentric or spiral information track, a first buffer area having a width wider than an access error when the last data in the recorded area is accessed, a recognition mark area in which no recording mark exists and a second buffer area having a width wider than an access error when the recognition mark area is accessed are recorded, comprises:
a rotating means for rotating the optical disc, an optical head for irradiating the information track with light beam generated from a light source, a retrieving means for retrieving the target information track, and a reading means for reading the information recorded on the information track; wherein the recorded area to be reproduced is specified by determining that no recording mark exists in the recognition mark area.
Furthermore, a third configuration of a reproducing device for an optical disc according to the present invention, information being reproduced from the optical disc in which, behind a recorded area in which information is recorded on a concentric or spiral information track, a first buffer area having a width wider than an access error when the last data in the recorded area is accessed, a recognition mark area in which no recording mark exists and a second buffer area having a width wider than an access error when the recognition mark area is accessed are recorded, comprises:
a rotating means for rotating the optical disc, an optical head for irradiating the information track with light beam generated from a light source, and a retrieving means for retrieving the target information track; wherein the recorded area to be reproduced is specified by retrieving the recognition mark area by the retrieving means and by determining that the recording mark cannot be retrieved.
Furthermore, it is preferable that the above-mentioned third configuration of a reproducing device for an optical disc according to the present invention further comprises a reading means for reading information recorded on the information track, and the recorded area to be reproduced is specified by determining that the recording mark cannot be read by the reading means.
Furthermore, a fourth configuration of a reproducing device for an optical disc according to the present invention, information being reproduced from the optical disc in which plural sets of a recorded area in which information is recorded, a first buffer area having a width wider than an access error when the last data in the recorded area is accessed, a recognition mark area and a second buffer area having a width wider than an access error when the recognition mark area is accessed are recorded on a concentric or spiral information track, wherein no recording mark is recorded in the last recognition mark area and a reproducible recording mark is recorded in the recognition mark areas other than the last recognition mark area, comprises:
a rotating means for rotating the optical disc, an optical head for irradiating the information track with light beam generated from a light source, a retrieving means retrieving the target information track, and a reading means for reading information recorded on the information track; wherein the last recorded area is specified by determining that no recording mark exists in the recognition mark area.
Furthermore, a fifth configuration of a reproducing device for an optical disc according to the present invention, information being reproduced from the optical disc in which plural sets of a recorded area in which information is recorded, a first buffer area having a width wider than an access error when the last data in the recorded area is accessed, a recognition mark area and a second buffer area having a width wider than an access error when the recognition mark area is accessed are recorded on a concentric or spiral information track, wherein no recording mark is recorded in the last recognition mark area and a reproducible recording mark is recorded in the recognition mark areas other than the last recognition mark area, comprises:
a rotating means for rotating the optical disc, an optical head for irradiating the information track with light beam generated from a light source, and a retrieving means for retrieving the target information track; wherein the last recorded area is specified by retrieving the recognition mark area by the retrieving means and by determining that the recognition mark area cannot be retrieved.
Furthermore, a sixth configuration of a reproducing device for an optical disc according to the present invention, information being reproduced from the optical disc in which plural sets of a recorded area in which information is recorded, a first buffer area having a width wider than an access error when the last data in the recorded area is accessed, a recognition mark area and a second buffer area having a width wider than an access error when the recognition mark area is accessed are recorded on a concentric or spiral information track, wherein no recording mark is recorded in the last recognition mark area and a reproducible recording mark is recorded in the recognition mark areas other than the last recognition mark area, comprises:
a rotating means for rotating the optical disc, an optical head for irradiating the information track with light beam generated from a light source, a retrieving means retrieving the target information track, and a reading means for reading information recorded on the information track; wherein the last recorded area is specified by retrieving the recognition mark area by the retrieving means and by determining that the recognition mark area cannot be read by the reading means.
Furthermore, a seventh configuration of a reproducing device for an optical disc according to the present invention, information being reproduced from the optical disc in which, behind a recorded area in which information is recorded on a concentric or spiral information track, a first buffer area having a width wider than an access error when the last data in the recorded area is accessed, a recognition mark area in which a reproducible recording mark is recorded, and a second buffer area having a width wider than an access error when the recognition mark area is accessed are recorded, comprises:
a rotating means for rotating the optical disc, an optical head for irradiating the information track with light beam generated from a light source, a retrieving means for retrieving the target information track, and a reading means for reading the information recorded on the information track; wherein the recorded area to be reproduced is specified by determining that the reproducible recording mark is recorded in the recognition mark area.
Furthermore, an eighth configuration of a reproducing device for an optical disc according to the present invention, information being reproduced from the optical disc in which, behind a recorded area in which information is recorded on a concentric or spiral information track, a first buffer area having a width wider than an access error when the last data in the recorded area is accessed, a recognition mark area in which a reproducible recording mark is recorded, and a second buffer area having a width wider than an access error when said recognition mark area is accessed are recorded, comprises:
a rotating means for rotating the optical disc, an optical head for irradiating the information track with light beam generated from a light source, a retrieving means for retrieving the target information track; wherein the recorded area to be reproduced is specified by retrieving the recognition mark area by the retrieving means and by determining that the recording mark can be retrieved.
Furthermore, it is preferable that the above-mentioned eighth configuration of a reproducing device for an optical disc according to the present invention further comprises a reading means for reading information recorded on the information track, and the recorded area to be reproduced is identified by determining that the recording mark area can be read by the reading means.
Furthermore, a ninth configuration of a reproducing device for an optical disc according to the present invention, information being reproduced from the optical disc in which plural sets of a recorded area in which information is recorded, a first buffer area having a width wider than an access error when the last data in the recorded area is accessed, a recognition mark area and a second buffer area having a width wider than an access error when the recognition mark area is accessed are recorded on a concentric or spiral information track, wherein a reproducible recording mark is recorded on the last recognition mark area and a non-reproducible recording mark is recorded on the recognition mark area other than the last recognition mark area, comprises:
a rotating means for rotating the optical disc, an optical head for irradiating the information track with light beam generated from a light source, a retrieving means for retrieving the target information track, and a reading means for reading information recorded on the information track; wherein the last recorded area is specified by determining that the reproducible recording mark exists in the recognition mark area.
Furthermore, a tenth configuration of a reproducing device for an optical disc according to the present invention, information being reproduced from the optical disc in which plural sets of a recorded area in which information is recorded, a first buffer area having a width wider than an access error when the last data in the recorded area is accessed, a recognition mark area and a second buffer area having a width wider than an access error when the recognition mark area is accessed are recorded on a concentric or spiral information track, wherein a reproducible recording mark is recorded on the last recognition mark area and a non-reproducible recording mark is recorded on the recognition mark area other than the last recognition mark area, comprises:
a rotating means for rotating the optical disc, an optical head for irradiating the information track with light beam generated from a light source, and a retrieving means for retrieving the target information track; wherein the last recorded area is specified by retrieving the recognition mark area by the retrieving means and by determining that the recognition mark area can be retrieved.
Furthermore, it is preferable that the above-mentioned tenth configuration of a reproducing device for an optical disc according to the present invention further comprises a reading means for reading information recorded on the information track, and the last recorded area is specified by determining that the recording mark area can be read by the reading means.